1. Field of the Invention
This invention relates to a two-dimensional image pickup apparatus and, more particularly, it relates to a two-dimensional image pickup apparatus adapted to X-ray photography.
2. Related Background Art
FIG. 1 of the accompanying drawings schematically illustrates a known image pickup apparatus adapted to X-ray photography and comprising a fluorescent member (e.g., scintillator) 1 for converting X-rays into rays of visible light, photoelectric converters 2a for converting visible light into electric signals, a substrate 2b that carries the photoelectric converter 2a, a base member 7 that supports the substrate 2b, circuit boards 5a, 5b for processing electric signals produced by photoelectric conversion, wires connected to the circuit boards, and an apparatus cabinet 8 containing the above components.
The substrate 2b arranged under the photoelectric converters 2a (hereinafter referred to simply as substrate) is typically made of glass because it is required to be free from chemical reactions with the photoelectric converters of semiconductor, resist the high temperature of the semiconductor forming process and maintain dimensional stability. The fluorescent member 1 is prepared by applying a fluorescent material of a metal compound to a resin plate. The gap separating the fluorescent member 1 and the photoelectric converters 2a has to be held to a sufficiently small value (typically less than tens of several micrometers) relative to the size of the pixels of the photoelectric converters 2a and, in most cases, the fluorescent member 1 and the substrate 2b are bonded together. Note that, in FIG. 1, photoelectric converter unit 102 refers to an assembly of a fluorescent member 1, a moisture-impermeable film 6 and other members arranged on the substrate 2b. 
When the photoelectric converters 2a are required to be moisture-resistant, the fluorescent member 1 and the photoelectric converters 2a may be wrapped and hermetically sealed by a moisture-impermeable and X-ray transmissive film 6. Then, they are bonded and securely held to the base member 7 before being placed in the apparatus cabinet 8 to complete the operation of assembling the image pickup apparatus for X-ray photography.
Such image pickup apparatuses are conventionally used as stationary apparatuses for X-ray photography. However, in recent years, there is an increasing demand for a lightweight, compact and portable image pickup apparatus adapted to rapid imaging operations and capable of producing fine images.
Additionally, image pickup apparatuses having the above described configuration are required to safeguard the substrate 2b and other related components against impacts that can be applied thereto during transportation. The apparatuses are also required to be safeguarded as a whole against deformations that can be caused by the external load (mainly the weight of the person to be photographed) applied to the apparatus during X-ray photographing operations. To meet these requirements, the apparatus cabinet 8 has to be structurally very robust and this necessity of being robust has been obstructing the attempt to down-size and reduce the weight of the apparatus.